MAC 10T Hub motor Repair

Ricky_nz

10 kW
Joined
Aug 15, 2010
Messages
844
Location
New Zealand
Hi All
Its been a long time since I logged in here.
Ive been busy with non ebike things but it finally happened and I managed to grind off most of the cable where it enters the axel of my MAC 10T. I have been putting about 25KM per day, 5 days a week on this thing.
So thought I would take a good look inside while I do it but it became difficult.

First off my carefully blue loctited in screws were very tight. I almost rounded one out before I got hold of a better set of alen keys. Yes mine had been replaced with Allen head countersunk screws because on my first rides I managed to lose most of the origional torx ones and they were what I could get.

I had to resort to my 1500W Hot air gun to heat up the screws and surrounding area one at a time and then just just hold a decent but not excessive amount of preassure on the key until they finally cracked loose. Looks like on some of them I put in too much loctite and it got under the countersunk head :oops: .

One screw was so bad even with a good Allen key it was felling like it was rounded out but I found a small amount of lime from the bike track came out when I scraped it out with the point of my smd tweezers and there was just enough engagment to get it out although I applied more heat first because this screw felt like the last amount of engagment wasen't going to last if I forced it.

Now with all the screws out I can get the cover of the side that opens to see the motor windings off and thats all good.
I want to check in the other side but thats the next problem. That cover won't break free from the Axle. I'm guessing the bearing has corroded to the shaft or something.
Currently trying to soak in some CRC cause Its all I have.

I want to fix this this weekend so I might have to skip looking in that side but I'm not sure if I need to pull the motor apart completely to replace the wires?

The hot air gun also works well to remove the epoxy over the connections on the hall sensor board.

Anyone got any ideas?

Thanks,
Ricky
 
Yup, been there done that!

There might be a few useful bits in the repair thread in my sig?

When I replaced wires I also drilled all the way through the axle and fitted bigger phase wires as well as wires for the temp sender which I put in. Good insurance. Rifle drilling the axle really needs a lathe though...
 
HI Spicerack,
Spicerack said:
There might be a few useful bits in the repair thread in my sig?
Thanks, I will have a good read, just skimemed so far.
I'm not pushing mine too hard since its my daily ride so I think I'll leave the axel as it is, My windings look like new which is unusal for me LOL.
.
It had the cellman upgraded wires in it but not sure how tight they are going to be to put back or even get the remaining part out.

I'm guessing I might need to see if I can borrow a puller from a firend to get the second cover to move.
 
spinningmagnets said:
Ricky, here's another thread that may be useful. Its a teardown of a MAC with lots of pics.

http://endless-sphere.com/forums/viewtopic.php?f=16&t=51310
Thanks

Lesson learnt though I was going to build a skid plate to protect the wires but never got arround to it so guess what I'm building after I fix it LOL.

I came off at very low speed 5 - 10Kph. The back wheel hit sliperty dried dead grass hanging over edge of concrete path heading uphill in heavy rain. The back wheel slipped off the edge of the concrete into the garden beside it dragging me down. No injories due to speed but the edge of the concrete throughly trashed the wires.
 
Well looking at the two threads above it looks like I really do need to get the cover and bearing on the planatery / wire side off the axel :(.

I don't have a puller so will probably try and borrow one if thats my best bet. Tapping the shaft gently hasen't given any hint of movement to I'm guessing its either corroded on or wedged tight with lime dust off the bike path.

I do ocasionally have to ride through very shallow salt water when there is a high tide (always wash off after) so I do suspect corrosion although nothing is visible. the axel I can see looks good.
 
I dunno squat about MAC motors but large soldering iron is what I use to soften bolts/screws secured with Loctite.
 
Ykick said:
I dunno squat about MAC motors but large soldering iron is what I use to soften bolts/screws secured with Loctite.
Thats a good idea The bolts are quite small, Nicely controlled.
My heat gun warmed up a larger section of the cover plate to maybe 60 deg C so not too bad but warmed a much larger area than an iron would
 
Hi All,
No progress :cry:
Well I haven't managed to find anyone with a suitable 3 jaw puller and since I'm busy saving for house renovations I don't really want to go out and buy one.

I have removed the wires completely and I can't see any way to put the thick phase wires back without full dissassembly of the motor. Please tell me if I'm wrong taking into account that I can't get the motor core out of the outter part due to the stuck bearing or tell me how to break the bearing free.

I have had a close look and it looks like the bearing on the wire entry side might be rusted onto the shaft explaining why it won't come out. Currently soaking overnight with CRC 556 again (all I have handy).

Any ideas on how to either get the side cover off the bearing so I can use a smaller puller or to free the stuck bearing off the shaft without a large puller?.

Riding my old GM 1000W hub with no rear brake is a little sketchy :lol:, I think I have the unused ebrake leavers for that in a box so since the mac is taking time I guess I better dig them out SO I can at least get regen brakeing

Thanks
Ricky
 
Well I didn't get the bearing to move.
I got a bit more aggressive with a club hammer (gental really but the exrtra weight helped) and got the motor core out but the bearing stayed attached to the axel and the side cover came off the bearing.
At least I can see more whats going on.

Rust, I suspected so but now I know for certain. I ride near / through (shallow on high tide) salt water (rinse as soon as possible afterwoods with fresh water) No choice on the route unless I have a death wish.
The inside of the motor is good but the bearing and the shaft show some rust.

At least now I would need a smaller bearing puller which hopefully one of my friends might own although I guess I could now get more drastic having access to the bearing now.
.
If I can get the bearing off I will probably put a new one on although it still feels smooth and in good condition.
I guess I should find something to put on the axel / bearing before reassembly to help prevent corrosion.

The photos show what I'm left with.
20140920_211030.jpg
20140920_210803.jpg
20140920_210431.jpg

Any ideas/opinions on the best way to remove this bearing?.
I am thinking I should lightly sand the visible part of the shaft to remove the thin corrosion on it first.
There is not too much space behind the bearing to grab it with a puller though.
 
I cleaned up the face of the bearing and the shaft with the wire wheel on my dremal.
Maybe i might have a chance of getting some CRC in the right place Now.
I need to find a suitable puller that can get in between the bearing and the side of the freewheel / sprocket carrier.

If I don't find a suitable puller to borrow of buy at the right price I might have to resort to butchery...
involving the cutoff wheel on my dremal to cut this bearing off since a new bearing is pretty cheap.
I would be worried about cutting too deep and hitting the axel though.
 
if you can't slide in a small puller you will never be able to use a cut disc of your dremel. you can reach into it.
just use 3 screwdrivers (120° apart from each other) of the same size and pry them between the bearing and the clutch/freewheel. you may need another person to help you to apply even force from all 3 sides. if you lift one side too much the bearing will not move at all.
good luck
 
izeman said:
just use 3 screwdrivers (120° apart from each other) of the same size and pry them between the bearing and the clutch/freewheel. you may need another person to help you to apply even force from all 3 sides. if you lift one side too much the bearing will not move at all.
Good idea thanks, I will try that first. Not sure how much corrosion is still present between the shaft and the bearing but definitly worth a go before getting destructive. Its still soaking at the moment.

Like you say clearance with the dremal cutoff wheel is probably an issue.
I thought about cutting parallel to the shaft first to remove the outer race and some of the inner race,
that would cut the outer in two places. Maybe a smaller grinding bit to finish it off but I guess it is better to avoid the
destructive methods if possible.
I guess there is a risk that I could trash the circlip behind the bearing but then again they are cheap.

Kind of worried now that I have the core out as the windings are exposed on the opposite side to the
bearing so I need to tape something over that side to protect it before I work on the bearing any more.
Just remembered Ive got a suitable piece of polystyrene that should do the trick out in the shed.
 
Ricky_nz said:
I ride near / through (shallow on high tide) salt water...
The inside of the motor is good but the bearing and the shaft show some rust.
Ricky_nz said:
I cleaned up the face of the bearing and the shaft with the wire wheel on my dremal.
Maybe i might have a chance of getting some CRC in the right place Now.

20140920_211030.jpg

First - the bearing is a close fit on a machined shaft and that is one gnarly looking shaft you have there. Your Dremel wire wheel is not going to clean it - it may polish off the surface rust, but the surface appears pretty corroded.

Get a 1" x 8" strip of mechanic's cloth (emery cloth or paper), loop it over the shaft and see-saw polish the rust off by alternately pulling on opposite ends. Keep moving in a circle around the shaft until the rust growths are removed and the surface is polished smooth. Tight tolerances on this portion of the axle are unimportant so get down to metal so the bearing can actually slide off. (Next time you remove a cover, do this first).

Next, CRC lube is just that - lube. It is worthless to loosen up rust. Go to an auto store or Home Depot an get a can of Blaster Rust Catalyst. This stuff actually dissolves rust. Be sure to pick up one of those little red tubes to go in the nozzle. Give this a try. It may not work, but it stands a 1000% better chance than CRC. Be careful squirting these kinds of solvents around - you don't want to get any flowing into the interior hidden clutch bearing or the grease will dissolve away (hence the little red tube and discretion).

Failing that, you can put the motor in the freezer overnight then use a torch with a narrow flame to heat ONLY the bearing prior to trying to pry it loose. You can prep for this by driving an awl into the exposed bearing shield and prying it out to expose more of the inner race for heating. It's important to get everything ready before you pull the motor from the freezer so the axle won't warm up. Use two blocks of wood in the vise to minimize warming the axle when you clamp it (test clamp, etc before the motor goes into the freezer). Working fast is key.
 
teklektik said:
...Working fast is key.
VERY fast i must say. :) and if you use a torch: use one with a really thin HOT flame. not one of those that plumbers use to solder tubes. use one to weld. a lot of concentrated heat in a very short time is key, while the axle needs to remain as cold as possible.
 
If you can't get the bearing off - cut it apart with a grinder.

I had a stuck bearing on the MAC and used a small angle grinder to remove it. It is much cheaper to buy a new bearing than purchase a bearing puller. Just take your time and you won't mark the axle.
 
Hi All,
Thanks for the ideas.
Yeah, I'm a software / electronics engineer so this mechanical stuff I figure out as I go and make mistakes :lol:.

Only used CRC cause Its what I had, kind of trying to avoid purchasing too much stuff because I'm saving for a big house renovation project.
I need to see whats available locally thats similar to that rust catalyst here in New Zealand.

I will definitly give the shaft a good clean up.
I have already given it a light sand with some fine grit wet and dry paper I had lieing arround for now.
I don't have access to anything with a hot enough flame so I won't do that.

I will probably just cut/grind this bearing off this weekend as it dosen't show any sign of moving and I'm pretty sure its rusted solid to the shaft.
Between the dremal and more likely my 4" angle grinder I guess I should be able to remove this one.
Don't want to do it during the week because the lighting isn't great in my shed plus I'm sure the neighbours don't want to hear an angle grinder after 9pm at night :lol:.

I have found some polystrene sheet to protect the other side of the motor when I clamp it down to work on it.
I will tape something over the gears which are in good nick) to protect them as much as possible although I have spares.

Interesting the shaft on the other side is fine, no rust what so ever. I think surplus oil from the chain / gear cluster etc might have got on the shaft and protected it.

Not sure best way to prevent the corrosion because I can't avoid the enviroment which caused it.

Edit:
Just had a look to see why I left the shaft looking rough when trying to remove the cover.
Looks like brake disk mount on the motor cover obsured the worst looking part of the shaft and I coulden't get anything near it to clean it up. Oh well covers off now with the bearing stuck to the shaft oops...

Think I've Found the blaster stuff
http://tradetools.co.nz/products/2850100
Hmm at $27NZ I think I'd rather just use the angle grinder .
A new bearing is cheaper for now but I should probably buy some after my renovation is complete as it looks useful stuff to have arround.
 
if you really want to cut off the bearing: use a big as possible disk (not those small 120mm ones) with a big grinder as this will allow you to access the bearing in a good angle. also cover the clutch/freewheel with duct tape all over it, as you want to avoid metal to go into the clutch itself!!
 
izeman said:
if you really want to cut off the bearing: use a big as possible disk (not those small 120mm ones) with a big grinder as this will allow you to access the bearing in a good angle. also cover the clutch/freewheel with duct tape all over it, as you want to avoid metal to go into the clutch itself!!
Ok Yep was going to cover the planatary gears and will also cover the clutch/freewheel.
I'll check with a few friends cause at least one probably has a bigger grinder than my one.
I can definitly see how bigger diameter would help access.
Thanks.

Just realised the PB blaster price I listed was excluding GST so thats $31NZ ($25USD) a can! We really get ripped off at this end of the world.
 
Ricky_nz said:
izeman said:
.also cover the clutch/freewheel with duct tape all over it, as you want to avoid metal to go into the clutch itself!!
Ok Yep was going to cover the planatary gears and will also cover the clutch/freewheel.
No - bag the entire motor (except for the bearing) in plastic and tape, otherwise the filings will will get sucked to the magnets and lams and you will never get them out. Gear motors are particularly nasty about this because of the (effectively) non-removable magnet can.

Ricky_nz said:
Just realised the PB blaster price I listed was excluding GST so thats $31NZ ($25USD) a can!.
Jeez - that sucks. It's good stuff, but not that good.... Around here it's cheap and available pretty much everywhere.
 
teklektik said:
No - bag the entire motor (except for the bearing) in plastic and tape, otherwise the filings will will get sucked to the magnets and lams and you will never get them out. Gear motors are particularly nasty about this because of the (effectively) non-removable magnet can.
Yep definitly don't want metal in the magnet can area! I will definitly make sure that side is well sealed up.
 
Got the bearing off :D
I didn't manage to borrow a bigger grinder so I ended up using my dremal since I am more precticed with it rather than my small angle grinder and since each had some access issues it didn't really matter.

The dremal being a bit slower to munch metal if put in the wrong place :lol:.

First of all I removed the bearing seal and purposly damaged the cage so it woulden't turn on me then.
Cut through the outter race with a thin metal cutting disc (disc parallel to shaft.and then once cut through in one place I pryed the cut outter race off (didn't take much) and removed the bearings and remains of the cage.
I was supprised at how little of the metal cutting disc it actually consumed, the bearing didn't seem too hard.

I used a cylindrical grinding attachment to grind through the inner.
I had to grind through it fully in two places as one was not enough to get it to move.
The first one I nicked the shaft but not enough to worry about and only in the thick part.
I swapped to a wider grinding attachment for the second.
After two grinds through and a few taps with hammer and punch I got the remains to slide off.
I didn't manage to get the two grinds exactly 180 apart so the second piece of bearing was a bit stubbon but still came off pretty easy.

There wasen't much corrosion under most of the bearing, mainly near the outter edge but I had not been successful in removing enough.

I will probably order a spare shaft next time I order parts from cellman.
I did manage to cut a section out of the wave washer but they are available locally from the same places as the bearing. The circlip is intact.

For the bearing I'm thinking of using one of these:
6903 VV: 17X30X7MM Ball Bearing Metric 2 Non Contact Rubber Seals NSK that is easy to get locally.
One more seal than the origional bearing. I figure the more seals the better considering the enviroment I put it in unless anyone knows of a reason not to use an additional seal.

Now I need to wipe down all the wrapping I had put on the motor to remove any metal particles before I unwrap it.
But before I do what I'll clean up the shaft a little more with some wet and dry sand paper.

I need to buy a bearing and wave washer next week. Should probably get some circlip pliers too.
I might check the hall and temp sensors this weekend though as most wires got cut/shorted when the cable got munched.
I also assume the controller will be damaged so got to get round to looking at that although its only a 6 fet and I have a bigger controller just waiting to plug in LOL.

I am thinking of swapping the temp sensor in the motor to be the correct type for the CAv3 as I have some here rather than the one cellman provided that I guess is possibly fried depending on the order of how things shorted.

Thanks

Edit:
just reading up on bearing types. The one I mentioned above probably isn't the best. The RS version is better, I didn't realise the difference. The VV version is non contact seal and the RS has contact sealing. Apparently the RS provides the best sealing so I will get a 6903 2RS. Contact seal on each side.
 
The couriers came today.

New Tool Time :D.

The other day I found a couple of the philips head screws inside the motor didn't look like they were going to turn without stripping so I brought an Impact Driver.View attachment 1Never used one before but worked really well. Just a gentle tap and it was all done :).

Also got some circlip pliers.resized006.pngAnother tool haven't used before.
I usually make do with needle nose pliers and screw drivers. Much nicer having the correct tool.

On the down side there goes my spending money for October...
Self imposed budget though but I need to stick to it for the planned house renovation.
 
Parts arrived today :D
parts.jpg
Since I ground a chunk out the side of the wave washer behind the bearing I got one of those. Also scraped the circlip so got some replacments.
Unfortunatly they didn't have a wave washer with a 17mm hole (EPL 13) so I got the next size up EPL 15 (19mm) center. On checking fit it looks like it is going to work and not rub on anything it shouldant although I would be happier with the EPL 13. It does get very close to the inner seal on the bearing though.
see http://www.farrellbearings.co.nz/site/farrellbearings/files/man cat/EMO brochure.pdf for the wave washer info.

As far as I can tell the wave washer has a similar wave depth to the one I damaged. the looser fit on the shaft is a small concern but it looks like it does contact the bearing inner race ok even when off center on the shaft.

The other bonus is I must have cleaned up the shaft enough because I carefully slid one of the new bearings onto the shaft and it slides all the way down the shaft to the clutch with no issues. I still need to get the freewheel/clutch off and its being stubborn so thats a job for later in the week, I should have a suitable puller to aid in removing it by then.

I am only going to replace the bearing that I cut off so the second is a spare along with the second wave washer :).
 
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